Back to EveryPatent.com
United States Patent | 6,064,632 |
Nakaoki ,   et al. | May 16, 2000 |
A recording/reproducing apparatus for use with a photomagnetic recording medium. The apparatus comprises a magnetic coil and an optical system having a numerical aperture (NA) greater than 0.8 and arranged such that an optical axis thereof traverses the center of the magnetic coil. The photomagnetic recording medium has a magneto-optic recording film and a transparent protective layer having a thickness HCO formed sequentially on a substrate. The magnetic coil and the optical system are arranged on the transparent protective layer side of the photomagnetic recording medium when the photomagnetic recording medium is used with the apparatus and such that a combined distance equal to the thickness HCO and a distance d between a surface of the magnetic coil and an adjacent surface of the photomagnetic recording medium has a value of 0 .mu.m.ltoreq.d.ltoreq.145 .mu.m. The thickness HCO of the transparent protective layer may have a value of 0 .mu.m.ltoreq.HCO.ltoreq.100 .mu.m, and the distance d may have a value not larger than 45 .mu.m. Additionally, an innermost radius Ri of the magnetic coil may have a value of 290 .mu.m or less.
Inventors: | Nakaoki; Ariyoshi (Tokyo, JP); Aratani; Katsuhisa (Chiba, JP); Kouchiyama; Akira (Kanagawa, JP) |
Assignee: | Sony Corporation (Tokyo, JP) |
Appl. No.: | 203629 |
Filed: | December 1, 1998 |
May 16, 1997[JP] | 9-127501 | |
May 19, 1997[JP] | 9-129027 |
Current U.S. Class: | 369/13.32 |
Intern'l Class: | G11B 011/00 |
Field of Search: | 369/13,283,288,286,275.1,275.2,275.4,46.14,118,110 360/59,114,102-103 |
5197049 | Mar., 1993 | Wehrenberg | 369/13. |
5684660 | Nov., 1997 | Gray et al. | 360/126. |
5703839 | Dec., 1997 | Ishii | 369/13. |
5872693 | Feb., 1999 | Yoda et al. | 360/126. |
5886959 | Mar., 1999 | Bischoff et al. | 369/13. |
5903525 | May., 1999 | McDaniel et al. | 369/13. |
5914915 | Jun., 1999 | Watanabe et al. | 369/13. |
5978320 | Nov., 1999 | Nakaoki et al. | 369/13. |